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Tkinter/Python3 app launch slow down each time it is killed instead of closed

The bug is present in the following setup:

  • Ubuntu 18.04.3 LTS (tested also on 20.04 LTS beta)
  • gnome-shell package is version 3.28.4-0ubuntu18.04.2
  • Linux x 4.15.0-96-generic #97 (closed)-Ubuntu SMP Wed Apr 1 03:25:46 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

Tested and problem reproducible on:

  • GNOME Flashback (Compiz) - default on my machine
  • Ubuntu on Wayland
  • GNOME on Xorg

Tested and problem is not detected on:

  • Live Kubuntu 18.04 LTS on other machine
  • vanilla LXDE installed in my Ubuntu 18.04.3 LTS

The problem is whenever a Tkinter/Python3 application I am working on is killed with Ctrl-C or killall python3 the subsequent launch of the application takes more time. When the window is closed with the X button no time is added to subsequent runs. When the user logs out and logs in launch time is back to the original.

I have attached a simple python script (slow.py) that demonstrates the issue. I also attached a bash script (runme) that runs the script in a loop and uses grep to print relevant time.

Steps to reproduce:

  1. run ./runme
  2. Close the window using the X symbol a number of time (e.g. 10 times)
    20640    0.206    0.000    0.206    0.000 {method 'call' of '_tkinter.tkapp' objects}
    20640    0.209    0.000    0.209    0.000 {method 'call' of '_tkinter.tkapp' objects}
    20640    0.233    0.000    0.233    0.000 {method 'call' of '_tkinter.tkapp' objects}
    20640    0.217    0.000    0.217    0.000 {method 'call' of '_tkinter.tkapp' objects}
    20640    0.207    0.000    0.207    0.000 {method 'call' of '_tkinter.tkapp' objects}
    20640    0.230    0.000    0.230    0.000 {method 'call' of '_tkinter.tkapp' objects}
    20640    0.215    0.000    0.215    0.000 {method 'call' of '_tkinter.tkapp' objects}
    20640    0.215    0.000    0.215    0.000 {method 'call' of '_tkinter.tkapp' objects}

The second column indicating time spent in all calls of the "call" method is consistent between calls.

  1. Kill the application, I use killall python3 run in a separate window. Do this a number of times (e.g. 10).
  2. Close the application with X (the first close reports wrong time, so please do this a couple of times)
    20640    1.331    0.000    1.331    0.000 {method 'call' of '_tkinter.tkapp' objects}
    20640    1.383    0.000    1.383    0.000 {method 'call' of '_tkinter.tkapp' objects}
    20640    1.321    0.000    1.321    0.000 {method 'call' of '_tkinter.tkapp' objects}
    20640    1.377    0.000    1.377    0.000 {method 'call' of '_tkinter.tkapp' objects}

Now the time spend in the "call" method is significantly higher.

  1. When the user logs out and in the time is back to about 0.210 until the app is killed with killall python3 or Ctrl-C

The problem is that the launch time of the app increased. The expected behavior is that there is no rise in launch time of the application. On other window managers - LXDE and KDE the problem does not manifest itself.

For the application I am working on the launch time increase is significant. Killing the application once adds about 6 seconds to the launch time.